The goal of the proposed studies is to understand how properties of single neurons of the somatic sensory system contribute to the tactile discriminative behavior of mammals. Specifically, we propose to examine neural responses to some spatio-temporal characteristics of cutaneous mechanical stimuli believed to be related to tactile form discrimination. Microelectrode recording will be from regions of representation of the ventral forepaw in the thalamic ventrobasal complex, and primary and secondary somatic sensory neocortex of unanesthetized raccoons. Single neuron discharges will be examined in response to (1) punctiform stimuli varying in velocity, depth of indentation, and locus of stimulation within the receptive field, (2) orientation of an extended stimulus, and (3) direction, rate of movement, and downward force of a stimulus moving parallel to the skin surface. The same types of stimuli will be applied to humam subjects, whose responses will be scaled by psychophysical methods.